The 35-year-old model-and-actress dumped the 'Snow White and the Huntsman' director in July 2012 after he was caught kissing the film's lead star Kristen - who was in a relationship with Robert Pattinson at the time.
Liberty - who also appeared in the movie playing Kristen's character Snow White's mother Queen Eleanor - admits the news hit her like an emotional bomb.
Talking in the December issue of Vanity Fair magazine, she said: ''I have no words to describe what we went through. But I think, for me, something always has to completely die for there to be a rebirth. And, for me, I feel like I'm going through a rebirth.
''It was horrible. It was really the worst, really the worst.''
Liberty - who has two children, son Tennyson and daughter Skyla, with Rupert - found it difficult to end her marriage but felt she ''didn't have any more to give''.
The actress - who filed for divorce from her spouse in January 2013 - explained: ''I'm not a quitter. I've done everything I could to be the perfect wife and mother and really support my husband. But I didn't have any more to give, you know?''
Rupert told her about the photos before they were published on the cover of Us Weekly magazine and she tried to be as strong as she could through the difficult period, focusing her efforts on how the 42-year-old filmmaker's actions would affect the family.
Liberty added: ''I was able to be completely secluded. I just visualised being this sort of Masai warrior. I was just going to stand very still and very strong, and just let it all roll past me. I tried to keep as far away from it as I could and to understand that this is my family and it's the most precious thing to me.''
Since filing for divorce, Liberty has been dating Interscope Records co-founder Jimmy Lovine this year.
Rob, 27, dumped Kristen in the summer after discovering Kristen, 23, had been back in contact with Rupert.
There's already an Oscars buzz surrounding this movie.